3D dynamic breast MRI: Pitfalls in diagnosis

Purpose: 3D dynamic contrast-enhanced MRI of the breast represents nowadays a worth diagnostic tool in breast pathology. Breast MRI accuracy depends on a correct selection of patients, otherwise you may easily mistake the diagnosis with heavy practical, economic and ethical implications. Material and method: In our institute we performed 297 breast MRI examinations for different clinical queries. We used a 3D-dynamic contrast-enhanced FSPGR sequence and a 1.5 T MR unit. Before the examination patients underwent a careful clinical-anamnestic evaluation; in fertile women MRI was carried out between 7th and 22th day of menstrual cycle; previous MRX and/or US examinations were reviewed; patients were recommended for the highest compliance in order to reduce motion and breathing artefacts. Results: Among 106 cases with an histological equivalent we observed 20 false results. The 6 false negative cases were performed before the 10th day of menstrual cycle (2 in situ carcinomas, 2 small fibroadenomas, 2 sclerotic adenosis). False positive results were 14: 6 due to a hormonal therapy recently suspended or still active, 4 due to the presence of the so-called UBOS (Unidentified Bright Breast Objects), 4 in which examination was performed after the 18th day of menstrual cycle. Conclusion: In literature breast MRI diagnostic accuracy varies from 65 and 90 %. This large variability is mostly due to pitfalls in cases selection and examination timing. We recommend an optimal examination timing (10th - 16th day of the menstrual cycle); a 6 months interval after hormone or radiotherapy.